Delicate Instruments Research Articles

II. On a new deep-sea thermometer

II. On a new deep-sea thermometer

Physical Laboratories

Physical Laboratories

The Problem of Mind, propounded to Metaphysics and Science

The Problem of Mind, propounded to Metaphysics and Science

XXXIII.—Description of a New Self-Registering Barometer

Although many proposals have been made to obtain a series of hourly meteorological observations by mechanical means, this desideratum has not, from various causes, been completely attained. The chief obstacle to be overcome, in such self-registering instruments, is the great amount of friction, which necessarily vitiates all the results, more especially in delicate instruments, such as the barometer and thermometer.Dr Robert Hooke was the first to propose a self-registered series of meteorological observations, by an instrument, which he quaintly called a Weather-wiser; but no further notice is taken of this contrivance than a short description in one of his tracts, bearing the date 5th December 1678, which would lead us to believe that the instrument was never used. The late Alexander Keith, Esq. of Ravelston also proposed a similar contrivance, a description of which is contained in this Society's Transactions, Vol. 4th. This contrivance, from the constant friction excited by the marker on the revolving paper, seems likewise to have been abandoned.

XXIII. Observations and experiments on the daily variation of the horizontal and dipping needles under a reduced directive power

It is now just a century since Mr. Graham discovered the daily change in the variation of the horizontal needle, subse­quent to which time numerous observations have been made on the same subject by Wargentin, Canton, Gilpin, Colonel Beaufoy and others, which have all confirmed, with certain shades of variety, the general fact as first described by the ingenious philosopher above named. The actual daily change however is so small, even in the horizontal needle, that it can only be detected with the most careful observations and with the most delicate instruments; and in the dipping needle that change, if any, is so extremely minute, as hitherto to have escaped observation : for it was only in the year 1820, that the Royal Academy of Sciences of Copenhagen proposed the determination of this motion, on satisfactory experiments, as the prize subject for that year; but the prize, I understand, has never been adjudged, no satisfactory communication having been received.